1. Field of the Invention
The invention relates to optical communication cables and somewhat more particularly to optical communication cable structures useful in high-voltage environments.
2. Prior Art
Because communication transmission via light signals over optical cables cannot be influenced by electric and or electromagnetic fields, such cables are extremely useful in high-voltage environments wherein systems or devices carry high voltage. Thus, it is known to utilize optical fiber light guides encased in a synthetic material in an area of a high-voltage overhead electrical line and/or to utilize a single or multi-lead glass fiber cable positioned within a center area of an overhead electrical conductor or in an outside covering of a phase-cable, for transmitting optical communication signals (for example see German OS 23 14 538; German OS 26 04 766 or German Utility Model 73 28 623). With such arrangements, the necessary spatial allocations for the optical and electrical compounds are provided during the manufacture of such overhead conductors. It is not possible to later install an optical cable on an already existing overhead line.
Optical communication cable structures are known which have hollow spaces within the cable core filled with a petrolatum-like mass to improve the friction relationship between the core element and to provide longitudinal moisture-impermeability to the resultant structure (for example see German OS 23 02 662 or German OS 24 29 670, which generally corresponds to British Patent Specification No. 1,445,732). Other known optical cable structures are comprised of only synthetic elements so that a metal-free cable structure is attained. In such cable structures, optical transmission elements in the form of glass fibers are surrounded with a loosely applied protective cover (for example see German OS 25 13 724 or German OS 25 51 210).